1. Field
The present general inventive concept relates to an image sensor including a source follower, and more particularly, to an image sensor including a source follower transistor having a gate to which a voltage that is dependent on charges accumulated in a photo detecting device is applied.
2. Description of the Related Art
Image sensors capture a subject and convert the subject into electric signals. Image sensors are not only used in general consumer electronic devices, such as digital cameras, mobile phone cameras, and mobile camcorders, but also in cameras installed in automobiles, security devices, and robots. Image sensors may include a pixel array. Light from the subject may be incident onto the pixel array via a module lens. The pixel array may include a plurality of pixels, and each of the plurality of pixels includes a photo detecting device. The photo detecting device may generate electric signals according to the intensity of absorbed light. For example, a photo diode may absorb light and thus generate a current.
The pixel may include a circuit for processing the electric signals generated by the photo detecting device. For example, the pixel may include at least one transistor. The at least one transistor may be controlled by applying a voltage, which depends on signals that are received from outside the pixel array, to a gate of the transistor. Also, the at least one transistor may amplify the electric signals generated by the photo detecting device. For example, a source follower transistor may output voltages, which depend on the voltage applied to the gate, through a source of the transistor. If errors of the voltages that are output by the source follower transistor are reduced, the signals that are output by the image sensors may more accurately reflect the intensity of the light that is absorbed by the photo detecting device. In addition, if the source follower transistor consumes less power, the image sensors may also consume less power.